Which of the following maintenance functions is not the responsibility of the GMDSS Radio Operator?

Correct Answer: Option D — Aligning the power output stage for maximum power.

Aligning the power output stage is a technical maintenance function requiring specialized knowledge and test equipment. This falls outside the scope of a GMDSS Radio Operator's license, which is limited to routine operational checks, visual inspections, and basic maintenance like battery testing or replacing consumables to ensure station readiness.